To do this with a steam turbine with the right equipment is reasonably simple. To do it with a small diesel engine is much more difficult as you have much less control of speed and phase, you have to make a pretty smart decision at the moment when it is right. I can't believe that you could ever do this with one component being turned by wind power. Even if you get in sync I doubt that it will hold in with the torque fluctuations from a windmill.

Synchrouus generators are not normally used with wind power without some form of hydraulic coupling or more commonly going through a dc link.

Normal small grid tie generators use an asynchronus generator or an alternator and dc link via an inverter.

DON'T ever try to connect a pm alternator to the grid.

Yes you can do this quite easily with a Synchronous Generator. Do a Google Search on this, and you'll find it's been discussed on this forum quite a bit as well.

Even standard ac motors can function as synchronous generators... just over drive their shaft speed fractionally faster than normal.

Make sure you have NO line capacitors on the motor, or it will generate and back feed into the grid if the grid happens to be down and you will electrocute line repairmen.

Most utility companies that I know of insist your system complies to meet their safety requirements and usually require an interface box which they sometimes what a fortune for : )

Play it safe and don't invite litigation.

Also yes you lock in your rotor speed by directly generating to the grid. If you have rather constant strong winds, this won't be a problem, but if you are in an area where this is not so, then you will not produce that much power.

All the older commercial wind generators worked like this, but they are moving on to higher technologies that allow them to take advantage in all kinds of wind situations.

Don't worry men,
I won't try it with a 10kw at full speed :)
In fact it seems indeed that asynchronous generators are
better for it,and cheaper.
If there are good DIY concepts of it,wy not.
But I got a renault 25 front wheel diskbrake hub
(fine,these a kind of things are for free) and
I'm really in for a 220V 50Hz xxxrpm generator.
Even if you have something between 120-230 V and
30-60Hz lots things can work on it like accuchargers
and computer powersupplies.
But certainly I will have some things to ask
about it and some things to show when I have a
digicam.
Thanks for the comments